Introduction to Polymer Science — DU B.Sc. Polymer Science Previous Year Question Papers

Attempt six questions in all. 1. (i) Discuss main reasons for the predominance of trans states in crystalline polyethylene. (1i) For a crystallizable polymer, crystallinity is much higher if it is crystallized from dilute solution than the melt stat. Justify this statement. (iii) Discuss advantages of flexural test over tensile test. (io) Consider the following polymers: • 5756 (c) -I-NH-CO-NH-CH2) na-and tensile strength. For fixed value, of n and x, discuss order of hydrophobic nature, density Discuss effect of free volume on glass transition temperature. 5x3 (i) Discuss salient features of fringed micelle mode.. (i), Why glass, is called super cooled liquid? Explain. x (iii) Show that the end-to-end distance of the freely jointed chain is expanded bond angle is tetrahedral. by a factor of when there is restriction to bond angles. Assume that the (a) Write possible structural and stereoisomers obtained from addition polymerization of butadiene. Show that the end-to-end distance of the freely jointed chain is expanded " by a factor of when there is restriction to bond 'angles. Assume that the bond angle is tetrahedral. Illustrate tacticity and diisotactcity of polymers with suitable examples. 4. (a) Illustrate breakdown voltage and power factor of à polymer. (b) Explain the following (itt) Yield point (iv) RMS end to end distance (u) Solubility parameter. 5: (a) Draw a log modulus temperature plot for an amorphous polymer. What are the five regions of viscoelasticity, and where do they fit? To which regions do the following belong at room temperature: chewing gum, rubber bands, PMMA ? (b) Discuss the principle of Florry Huggins theory. (c) Give detailed classification, of polymers on the basis of end use. 5,5,5 6. (a) What is the role of molecular weight in determining properties of a polymer? Elaborate with examples. (b) Discușs heterogeneity of molecular weight of a polymer. Explain the following fluids with examples: 5,5,5 Calculate the molecular weight of the polymer having -HN (CH25 CO-as repeating unit if the degree of polymérization is 1000. (b) Define conformation of a polymer. Discuss stable conformations with suitable examples. (c) Explain the relationship of molecular size with intrinsic viscosity.